Cases and solutions 56 Environmental Geology 32 (1) July 1997 7 Q Springer-Verlag Received: 2 May 1996 / Accepted: 14 October 1996 Y. S. Rao (Y) 7 T. V. K. Reddy 7 P. T. Nayudu Department of Geology, S. V. University, Tirupati - 517502, India Groundwater quality in the Niva River basin, Chittoor district, Andhra Pradesh, India Y. Srinivasa Rao 7 T. V. K. Reddy 7 P. T. Nayudu Abstract This study was made to assess the groundwater quality in relation to agricultural and domestic uses in a part of the Peninsular Archean granite and gneissic complex of India. Water sam- ples were collected from the existing wells in the Niva River basin, Chittoor district, Andhra Pradesh, India and analysed for major ions. The analytical data, processed and interpreted acoording to the WHO standards, reveal that, in general, the groundwater is suitable for both agricultural and domestic uses, exept in a few locations. High con- centration of nitrates were observed in some of the wells (both agricultural and domestic) that are af- fected by the impact of industrial effluents. Multi- ple regression analysis was performed and used as a positive predictive tool in understanding the chemistry of the groundwater. Key words Groundwater quality 7 Pollution 7 Nitrates 7 Total dissolved solids 7 Regression analysis Introduction The quality of water plays a prominent role in promoting both the standard of agricultural production and human health. If deterioration starts in water quality it will natu- rally affect the soil-crop-water system and human health conditions. In the initial period of water quality deterio- ration the damage may be low, but if it is not controlled at the right time, this water will not be suitable for any purpose. Water quality may vary depending upon varia- tion in geological formations. Human activity such as in- dustrialization, mining and urbanization may also pro- duce effluents which pollute the environment. Keeping these points in mind, an attempt was made to study the qualitative analyses of groundwater and also to detect the causes for the deterioration of water quality, by collecting 59 groundwater samples in the Niva River basin, Chittoor district, Andhra Pradesh, India. The Niva River basin lies between the latitudes 13702b–13716b N and longitudes 78753b3n–79709b4n E with a catchment area of 359 km 2 . Geologically, the basin is underlain by rocks of Archean age consisting of granites, granite- gneisses, recent alluvium and soils. Numerous dolerite dykes occur as intrusions in the granites and gneisses (Central Ground Water Board 1975; Geological Survey of India 1980). The Niva River rises from the Paradarami hill ranges in Chittoor district and flows through the town of Chittoor (the headquarters of Chittoor district) and finally joins the Ponnai River as a tributary near the village of Kotra- kona in the Chittoor district of Andhra Pradesh. The groundwater occurs both under unconfined and semicon- fined conditions and the aquifers are mainly weathered and fractured granites, gneisses, and contact zones of crushed dykes with the granites and gneisses. The depth to the water table varies from 3.5 m to 22 m. Chittoor is a fast growing town with a population of 1.3 lakhs [130,000 (Census of India 1991)]. Sugar, distille- ry, dairy and other industries in and around the town of Chittoor discharge their effluents into the nearby streams and ponds without proper treatment. Against this back- ground, the authors undertook further studies of ground- water to determine its quality and classify the quality of water used for different purposes. Materials and methods A total of 59 groundwater samples from the working dug, dug-cum-bore and bore wells of the basin area were col- lected during July 1991. The locations of the collected groundwater samples are shown in Fig. 1. The samples were analyzed for different ions and interpreted by stand- ard methods [American Water Work Assocation (AWWA) 1950; Rainwater and Thatcher 1960; Brown et al. 1970] in order to study the quality of water for var- ious purposes. Electrical conductivity (EC) and concen- tration of nitrates contour maps were prepared. The minimum and maximum values of major ions of